Device for adjusting form rollers providing automatic compensation for change in packing thickness

Abstract

A printing press having a plate cylinder and a cooperating cylinder, a layer of packing being interposed under the plate. A film of ink is applied to the plate by a plurality of form rollers. An eccentric bushing is interposed between the plate cylinder and the frame of the press rockable from a reference position to an adjusted position for increasing the spacing between the axes of the plate cylinder and its cooperating cylinder as necessary to accommodate an increase in the thickness of the packing. A cam sector is mounted at the end of the plate cylinder having spirally curved segments for radially supporting the rollers with respect to the plate and mounted for rocking movement for camming the rollers relatively away from the axis of the plate cylinder. The cam sector is rotatively coupled to the eccentric bushing for rocking movement in unison therewith and the spiral slope of each of the curved segments is such that the degree of rocking of the eccentric bushing necessary to accommodate a predetermined increase in packing thickness causes a total outward throw at each of the form rollers equal to the movement of the plate cylinder axis toward the form roller axis plus an amount equal to the added thickness of the packing, with the result that the spacial relationship between the form rollers and the plate is unaffected by a change in the thickness of the packing. In the preferred embodiment the cam sector is fixed to the eccentric bushing. Provision is made for individual adjustment of the radial position of each curved segment.

What I claim is: 
     
       1. In a printing press, the combination comprising a frame, a plate cylinder journaled in the frame and mounting a printing plate with a layer of packing interposed between the cylinder and the plate, a cooperating cylinder journaled in the frame running in engagement with the plate, the plate cylinder having at least one form roller having a bearing at a peripheral position substantially spaced from said cooperating cylinder, an eccentric bushing interposed between the plate cylinder and the frame rockable from a reference position t an adjusted position for increasing the spacing between the axes of the plate cylinder and its cooperating cylinder as necessary to accommodate an increase in the thickness of the packing, a cam sector rockably mounted at the end of the plate cylinder having a spirally curved segment for radially supporting the form roller bearing with respect to the plate and mounted for rocking movement for camming the roller relatively away from the axis of the plate cylinder, the cam sector being rotatively coupled to the eccentric bushing for rocking movement in unison therewith accompanied by relative wiping action between the curved segment and the roller bearing, the spiral slope of the curved segment being such that the degree of rocking of the eccentric bushing necessary to accommodate a predetermined increase in packing thickness causes a total outward throw at the form roller equal to the movement of the plate cylinder axis toward the form roller plus an amount equal to the added thickness of the packing. 
     
     
       2. In a printing press, the combination comprising a frame, a plate cylinder journaled in the frame and mounting a printing plate with a layer of packing interposed between the cylinder and the plate, a cooperating cylinder journaled in the frame running in engagement with the plate, the plate cylinder having at least one form roller having a bearing at a peripheral position substantially spaced from the said cooperating cylinder, an eccentric bushing interposed between the plate cylinder and the frame rockable from a reference position to an adjusted position for increasing the spacing between the axes of the plate cylinder and its cooperating cylinder as necessary to accommodate an increase in the thickness of the packing, a cam sector rockably mounted at the end of the plate cylinder and having a spirally curved segment for radially supporting the roller with respect to the plate, the cam sector being rigid with the eccentric and movable therewith to produce relative wiping movement between the curved segment and the roller bearing for camming the roller relatively away from the axis of the plate cylinder, the spiral slope of the curved segment being such that the degree of rocking of the eccentric bushing necessary to accommodate a predetermined increase in packing thickness causes a total outward throw at the form roller equal to the movement of the plate cylinder axis toward the form roller plus an amount equal to the added thickness of the packing. 
     
     
       3. The combination as claimed in claim 2 in which the curved segment lies substantially in the locus of a circle whose center P lies on a straight line interconnecting the plate cylinder axis and the eccentric bushing axis, with the center P being spaced from the bushing axis by an amount which is twice as great as the spacing between the plate cylinder axis and the bushing axis. 
     
     
       4. In a printing press, the combination comprising a frame, a plate cylinder journaled in the frame and mounting a printing plate with a layer of packing interposed between the cylinder and the plate, a cooperating cylinder journaled in the frame in running engagement with the plate, the plate cylinder having a plurality of form rollers having respective bearings at peripheral positions spaced from one another and all of which are substantially spaced from the said cooperating cylinder, and eccentric bushing interposed between the plate cylinder and the frame rockable from a reference position to an adjusted position for increasing the spacing between the axes of the plate cylinder and its cooperating cylinder as necessary to accommodate an increase in the thickness of the packing, a cam sector rockably mounted at the end of the plate cylinder having spirally curved segments for radially supporting the roller bearings with respect to the plate and mounted for rocking movement for camming the rollers relatively away from the axis of the plate cylinder, the cam sector being rotatively coupled to the eccentric bushing for rocking movement in unison therewith accompanied by relative wiping action between the curved segments and the respective roller bearings, the spiral slope of each of the curved segments being such that the degree of rocking of the eccentric bushing necessary to accommodate a predetermined increase in packing thickness causes a total outward throw at each of the form rollers equal to the movement of the plate cylinder axis toward the form roller plus an amount equal to the added thickness of the packing and the curved segments having a common center with the result that the spacial relationship between the form rollers and the plate is unaffected by a change in the thickness of the packing. 
     
     
       5. In a printing press, the combination comprising a frame, a plate cylinder journaled in the frame and mounting a printing plate with a layer of packing interposed between the cylinder and the plate, a cooperating cylinder journaled in the frame running in engagement with the plate, the plate cylinder having a plurality of form rollers having respective bearings at peripheral positions spaced from one another and all of which are substantially spaced from the said cooperating cylinder, an eccentric bushing interposed between the plate cylinder and the frame rockable from a reference position to an adjusted position for increasing the spacing between the axes of the plate cylinder and its cooperating cylinder as necessary to accommodate an increase in the thickness of the packing, a cam sector fixed to the eccentric bushing for rocking movement in unison therewith, the cam sector having a plurality of spirally curved segments for radially supporting the roller bearings with respect to the plate and mounted for rocking movement for camming the rollers relatively away from the axis of the plate cylinder, the spiral slope of the respective curved segments being such that the degree of rocking of the eccentric bushing necessary to accommodate a predetermined increase in packing thickness causes a total outward throw at each of the form rollers equal to the movement of the plate cylinder axis toward the form roller plus an amount equal to the added thickness of the packing, with the result that the spacial relationship between the form rollers and the plate is unaffected by a change in the thickness of the packing, the curved segments lying respectively in the loci of circles having a common center P lying on a straight line interconnecting the plate cylinder axis and the eccentric bushing axis, with the center P being spaced from the bushing axis by an amount which is twice as great as the spacing between the plate cylinder axis and the bushing axis. 
     
     
       6. The combination as claimed in claim 4 in which means are interposed between each of the curved segments and the cam sector for individual adjustment of the radial position of each curved segment for determining the initial spacial relationship between the form rollers and plate using an initial thickness of packing. 
     
     
       7. The combination as claimed in claim 6 in which each position adjustment means is in the form of an eccentric driven by a worm and worm wheel.